Until yesterday I had not cleaned my 6mm Ackley in almost 350 rounds. It shot a 3 inch group at 600 yards, then all of a sudden it quit shooting. I figured it was the fact that I had not cleaned the barrel in "forever". After I got home to clean the barrel it turned out the rings had worked loose and let the scope slip. I have a feeling the 6mm would have kept on shooting fine if it wasn't for the ring issues. I've never had a gun "quit shooting" because I hadn't cleaned it in X number of rounds, but people say you have to clean really overbore chamberings every 10 or 15 rounds. Why is this? Does it effect barrel life or fouling?